Crosslinkable coating compositions

ABSTRACT

An aqueous crosslinkable coating composition comprising i) an autoxidizably crosslinkable polymer, ii) a not autoxidizably crosslinkable vinyl polymer bearing carbonyl groups and iii) carbonyl-reactive groups to crosslink the vinyl polymer.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is the National Phase of International ApplicationPCT/GB00/01011 filed Mar. 17, 2000 which designated the U.S. and thatInternational Application was published under PCT Article 21(2) inEnglish.

FIELD OF THE INVENTION

The present invention relates to aqueous-based autoxidisablycrosslinkable coating compositions, their preparation and use in formingfilms and coatings.

BACKGROUND OF THE INVENTION

Autoxidisably crosslinkable polymers are polymers which crosslink onexposure to oxygen. It is known that polymers which contain unsaturatedfatty acid residues undergo crosslinking by autoxidation. Theunsaturation in polymers from such groups imparts latentcrosslinkability so that when a coating composition thereof is dried inair (often in conjunction with a drier salt) the composition undergoescrosslinking, thereby improving its properties such as mechanicalproperties (improved hardness and durability) and chemical resistance. Afurther advantage of coatings containing unsaturated fatty acid residuesis an improved glossy appearance. EP 379007, EP 0017199 and EP 647655all describe a one component emulsion which contain autoxidisablepolymers with carboxylic acids groups to provide water dispersibility.

However disadvantages of autoxidisably crosslinkable polymers containingunsaturated fatty acid residues are that the curing process is slow(typically taking a period of days) and that yellowing of the coatingoccurs in time.

It is known in, for example, U.S. Pat. No. 4,198,811 and WO97/26303 toblend autoxidisably crosslinkable polymers with acrylic polymerdispersions to reduce yellowing and in some cases cost, however theperformance of the resulting coatings, in particular the mechanicalproperties and the resistance to chemicals is greatly reduced.

BRIEF SUMMARY OF THE INVENTION

We have surprisingly found that compositions of autoxidisablycrosslinkable polymers containing unsaturated fatty acid residues with apolymer which is not autoxidisably crosslinkable, but has certain othercrosslinking means, not only reduces the cure time and yellowing ofcoatings derived from such a composition, but also that the performanceof such a composition in other respects (such as the mechanicalproperties and chemical resistance) is not vitiated and is comparable toan improvement to the performance of the autoxidisable crosslinkablepolymer containing unsaturated fatty acid residues alone.

According to present invention there is provided an aqueouscrosslinkable coating composition comprising as aqueous dispersedcomponents:

i) at least one autoxidisably crosslinkable organic polymer containingunsaturated fatty acid residues, and

ii) at least one vinyl polymer which is not autoxidisably crosslinkableand bears carbonyl functional groups, and wherein said composition haspresent therein carbonyl-reactive amine and/or hydrazine functionalgroups which impart crosslinkability to component (ii).

DETAILED DESCRIPTION OF THE INVENTION

For the sake of clarity by a carbonyl functionality in thisspecification (unless specified otherwise) is meant the carbonylfunctionality of a ketone or aldehyde group. Such carbonyl functionalgroups in a vinyl polymer are normally chain-pendant and/or terminalgroups.

By a hydrazine functional group is meant a carbonyl-reactive functionalgroup of formula —NHNH₂ and also a carbonyl-reactive hydrazone groupderived from such a group by reaction with a monoketone or monoaldehydeof at least two carbon atoms. It will become apparent that suchfunctional groups are usually part of larger groups, such as those offormulae, —R—C(═O)—NH—NH₂, —R—C(═O)—NH—N═C<, —R—NH—C(═O)NH—NH₂,—R—NH—C(═O)—NH—N═C<, and —R—NH—NH₂ where R is optionally substitutedalkylene, optionally substituted alicyclic, or optionally substitutedaryl.

By an amine functional group is meant a carbonyl-reactive group offormula —NH₂ and carbonyl-reactive groups derived from such groups.Examples of amine functional groups include R—NH₂, R—O—NH₂, R—O—N═C<,—R—NH—C(═O)—O—N═C< and —R—NH—C(═O)—O—NH₂ where R is as described above.

By an autoxidisably crosslinkable polymer is meant a polymer whichcrosslinks on exposure to oxygen from air by virtue of containingunsaturated fatty acid residues.

By a not autoxidisably crosslinkable polymer is meant a polymer notcontaining unsaturated fatty acid residues.

For the purpose of this invention an “aqueous dispersion” of apolymer(s) means a dispersion of polymer(s) in a liquid carrier mediumof which water is the principle component (at least 50 weight %, moreusually at least 80 weight %, of the carrier medium). Minor amounts oforganic liquids may optionally be present. The dispersion will typicallycomprise colloidally dispersed particles of the polymer(s), i.e. willtypically be in the form of an aqeuous latex(ices).

Preferably the autoxidisably crosslinkable organic polymer containingunsaturated fatty acid residues is a polyurethane polymer. Othersuitable polymers include alkyds which may be self-emulsifiable,water-based or emulsified alkyds.

In the invention composition, the carbonyl-reactive amine and/orhydrazine functional groups impart crosslinkability to the vinylpolymer(s) of component (ii) by virtue of the latter bearing carbonylfunctional groups. It is nevertheless within the scope of the invention,albeit less preferred, for such amine and/or hydrazine functional groupsto also impart crosslinkability to the polymer(s) of component (i) ifthis polymer(s) also bears carbonyl-functional groups—as is possible,but less preferred.

The disposition of the amine and/or hydrazine functional groups in theinvention composition to impart crosslinkability as defined may berealised in various ways. More preferably hydrazine functional groupsare used in the invention composition.

In a preferred embodiment, the carbonyl-reactive amine and/or hydrazinefunctional groups are present in the composition by virtue of beingprovided by added discrete compounds bearing 2 or more amine groups,hereinafter called polyamines, or 2 or more hydrazine functional groups,hereinafter called polyhydrazines. By “discrete” is meant that suchcompounds are exclusive of the polymers of components (i) and (ii).Preferably the polyamines or polyhydrazines are diamines or triamines(i.e. having 2 or 3 amine groups) or dihydrazines (i.e. having 2hydrazine functional groups).

The presence of such a polyamine or polyhydrazine will impartcrosslinkability to the vinyl polymer(s) of component (ii). However, ifthe polymer(s) of component (i) also bears carbonyl functional groups(as is possible as discussed above), such a polyamine or polyhydrazinewill also impart crosslinkability to this polymer(s) of component (i) byreaction with the carbonyl functional groups thereof, i.e. in additionto crosslinkability by autoxidisation.

It is, furthermore, also possible for amine and/or hydrazine functionalgroups to be borne on the polymer(s) of component (i), i.e. theautoxidisably crosslinkable organic polymer containing unsaturated fattyacid residues could also bear carbonyl-reactive amine or hydrazinegroups, thereby allowing the organic polymer(s) to undergo crosslinkingby reaction with the carbonyl functional groups of the vinyl polymer(s)as well as crosslinking by autoxidation.

As discussed above, the polymer of component (i) in this embodiment mayitself also bear carbonyl functional groups, and in such a casecrosslinkability could also be provided by reaction between thepolymer-based amine or hydrazine groups of the polymer(s) of component(i) and the polymer-based carbonyl functional groups of the polymer(s)of component (i) (in addition to that by reaction with the polymer-basedcarbonyl functional groups of the vinyl polymer(s) of component (ii)).

In a yet further embodiment, the not autoxidisably crosslinkable vinylpolymer(s) of component (ii) may in addition to bearing carbonylfunctional groups also bear carbonyl-reactive amine or hydrazine groups.In such a case, crosslinkability could be provide by reaction betweenthese polymer-based carbonyl functional groups and polymer-based amineor hydrazine groups of the vinyl polymer(s) of component (ii) (ifpresent).

It is apparent from the foregoing, that more than one of suchembodiments could be operative in the same invention composition.However, in the most preferred embodiment, the amine and/or hydrazinegroups are present only in discrete added polyamines and/orpolyhydrazines and the carbonyl functional groups are present only inthe vinyl polymer(s) of component (ii). Alternatively a mixture ofdiscrete added and polymer based amine and/or hydrazine groups may beemployed.

Autoxidisably crosslinkable polyurethane polymers containing unsaturatedfatty acid residues are preferably obtained from the reaction of atleast one organic polyisocyanate with at least one isocyanate-reactiveorganic compound bearing unsaturated fatty acid residue(s), optionally(but preferably) with isocyanate-reactive organic compounds bearingwater-dispersing groups, and in some embodiments (as implied above),isocyanate-reactive compounds bearing carbonyl and/or carbonyl-reactiveamine or hydrazine groups. Optionally, the reactants may also include alow molecular weight isocyanate-reactive compound(s) (preferably with amolecular weight of below 500), usually an organic polyol and/or a highmolecular isocyanate-reactive compound(s) (preferably with a molecularweight of from 500 to 6000), also usually an organic polyol—suchcompounds, if used, bearing neither unsaturated fatty acid residue(s)nor water—dispersing groups. Isocyanate-reactive groups include —OH,—NH—, and —NH₂.

The polyurethane polymer may be prepared in a conventional manner byreacting the organic polyisocyanate(s) with the isocyanate-reactivecompound(s) by methods well known in the prior art. Preferably anisocyanate-terminated polyurethane prepolymer is first formed, which ischain extended with an active hydrogen containing compound. If thepolymer is made in such manner, the unsaturated fatty acid residue(s)bearing compound is introduced into the polyurethane backbone during theprepolymer formation and/or during the chain extension step. Theoptional polymer-based carbonyl, amine or hydrazine groups (see supra)may also be introduced during the prepolymer formation and/or during thechain extension step.

Alternatively a polyurethane (preferably of a low molecular weight) maybe made by capping an isocyanate-terminated polyurethane withmonofunctional isocyanate-reactive compounds or by using an excess ofcompounds having isocyanate-reactive groups during polymer preparationor a combination of the above preparations may be used.

Optionally (but preferably) monomer(s) bearing non-ionic or ionicwater-dispersing or emulsifier groups (or groups that may besubsequently converted thereto) are included in the prepolymer formationto provide the facility of self-dispersability in water of thepolyurethane prepolymer and the final autoxidisably crosslinkablepolyurethane polymer.

Preferred isocyanate-reactive compounds bearing unsaturated fatty acidresidue(s) which may be used in the urethane synthesis may be obtainedfrom the reaction, using techniques known in the art, of a suitablefatty acid with a hydroxyl donor (preferably an alcohol or polyol) oramine donor to provide a fatty acid residue-bearing compound with atleast one (preferably at least two) hydroxyl or amineisocyanate-reactive groups.

Preferred fatty acids include fatty acids derived from castor oil,soybean oil, sunflower oil, tallow oil, linseed oil and fatty acids suchas linoleic acid, palmitoleic acid, linolenic acid, oleic acid,oleosteric acid, licanic acid, arachidonic acid, ricinoleic acid and/ormixtures thereof.

Suitable polyisocyanates include aliphatic, cycloaliphatic, araliphaticand/or aromatic polyisocyanates. Examples of suitable polyisocyanatesinclude ethylene diisocyanate, 1-6-hexamethylene diisocyanate,isophorone diisocyanate, cyclohexane-1,4-diisocyanate,4,4′-dicyclohexylmethane diisocyanate, p-xylylene diisocyanate,tetramethylxylene diisocyanate, 1,4-phenylene diisocyanate, 2-4-toluenediisocyanate, 2,6-toluene diisocyanate, 4,4′-diphenylmethanediisocyanate, polymethylene polyphenyl polyisocyanates2,4′-diphenylmethane diisocyanate, 3(4)-isocyanatomethyl-1-methylcyclohexyl isocyanate, and 1,5-naphthylene diisocyanate. Mixtures ofpolyisocyanates can be used and also polyisocyanates which have beenmodified by the introduction of urethane, allophanate, urea, biuret,carbodiimide, uretonimine, urethdion or isocyanurate residues.

Other isocyanate-reactive organic compounds bearing neither unsaturatedfatty acid residues nor water-dispersing groups (see supra) which may beused in the preparation of polyurethanes or polyurethane prepolymerspreferably contain at least one (preferably at least two)isocyanate-reactive groups, and are more preferably organic polyols. Theorganic polyols particularly include diols and triols and mixturesthereof but higher functionality polyols may be used, for examples asminor components in admixture with diols. The polyols may be members ofany of the chemical classes of polyols used or proposed to be used inpolyurethane formulations. In particular the polyols may be polyesters,polyesteramides, polyethers, polythioethers, polycarbonates,polyacetals, polyolefins or polysiloxanes. Preferred polyol molecularweights are from 250 to 6000, more preferably from 500 to 3000. Lowmolecular weight organic compounds containing at least one (preferablyat least two) isocyanate-reactive groups and having a weight averagemolecular weight up to 500, preferably in the range of 40 to 250 canalso be used. Examples include ethyleneglycol, 1-propanol, and1,4-cyclohexyldimethanol.

The water-dispersing group content of the polyurethane (if present) mayvary within wide limits but should be sufficient to provide thepolyurethane with the required degree of water-dispersibility.

Water-dispersing groups are optionally incorporated into thepolyurethane by including an isocyanate-reactive and/or isocyanatecompound(s) bearing nonionic and/or ionic water-dispersing groups (orgroups which may be subsequently converted to such water-dispersinggroups) as reactants in the preparation of the polymer or prepolymer.

Typically, ionic water-dispersing groups are anionic salt groups, forexample carboxylate, sulphonate and phosphonate salt groups. Examples ofsuch compounds include carboxy group containing diols and triols, forexample dihydroxy alkanoic acids. The preferred carboxy containing diolis 2,2-dimethylolpropionic acid or 2,2-dimethylolbutanoic acid. Ifdesired, the carboxy containing diol or triol may be incorporated into apolyester by reaction with a dicarboxylic acid before being incorporatedinto the prepolymer. The conversion of any acid groups present in theprepolymer to anionic salt groups may be effected by neutralising thesaid acidic groups before, after or simultaneously with formation of anaqueous dispersion of the prepolymer.

Non-ionic water-dispersing groups are preferably pendant polyoxyalkylenegroups, particularly polyoxyethylene groups.

The polyurethane polymer or prepolymer may have a combination of ionicdispersing groups and non-ionic water-dispersing groups.

A carbonyl functional group may be introduced onto a polyurethanebackbone by using for example carbonyl functional compounds with atleast one and preferably two isocyanate-reactive groups, for exampledihydroxyketones or the adduct obtained by a Michael addition reactionof diacetonacrylamide with a diamine or an alkanol amine.

An amine or hydrazine functional group may similarly be introduced ontoa polyurethane backbone. For example a compound is used in which thehydrazine functionality has been blocked by reaction with a monoaldehydeor a monoketone to form a hydrazone structure. This expedient isemployed because a hydrazine functionality will otherwise react duringthe prepolymer preparation and so be partially or even completelyremoved.

Examples of suitable isocyanate-reactive monoaldehyde or monoketonehydrazine compounds include gammahydroxy butyric hydrazide and semicarbazide ethyl methacrylate blocked with a monoaldehyde or monoketone.

Active hydrogen-containing chain extending compounds which providehydrazine (or hydrazone) functionality pendant to the polyurethane chaininclude diamino hydrazides. Such compounds may be prepared by reacting adiamine with an acrylic acid derivative (for example ethyl acrylate) andthen reacting the product obtained with hydrazine.

When an isocyanate-terminated polyurethane prepolymer is prepared, it isconventionally formed by reacting a stoichiometric excess of the organicpolyisocyanate with the isocyanate-reactive compounds undersubstantially anhydrous conditions at a temperature between about 30° C.and about 130° C. until reaction between the isocyanate groups and theisocyanate-reactive groups is substantially complete; the reactants forthe prepolymer are generally used in proportions corresponding to aratio of isocyanate groups to isocyanate-reactive groups of from about1.1:1 to about 6:1, preferably from about 1.5:1 to 3:1.

If desired, catalysts such as dibutyltin dilaurate and stannous octoate,zirconium or titanium based catalysts may be used to assist prepolymerformation. An organic solvent may optionally be added before or afterprepolymer formation to control the viscosity. Examples of solventsinclude water-miscible solvents such as N-methylpyrrolidone, dimethylsulphoxide and dialkyl ethers of glycol acetates or mixtures ofN-methylpyrrolidone and methyl ethyl ketone. Optionally no organicsolvents are added.

An aqueous polyurethane dispersion may then be prepared by dispersingthe isocyanate-terminated polyurethane prepolymer (optionally carried inan organic solvent medium) in an aqueous medium (using surfactants, ormore preferably by utilising the self-dispersability of the prepolymerif dispersing groups are present therein, although surfactants may stillbe employed if desired) and chain extending the prepolymer with activehydrogen-containing chain extender in the aqueous phase.

The aqueous polyurethane dispersion may of course comprise more than onepolyurethane polymer prepared as defined above.

The urethane prepolymer may be dispersed in water using techniques wellknown in the art. Preferably, the prepolymer is added to the water withagitation or, alternatively, water may be stirred into the prepolymer.

Active hydrogen-containing chain extenders which may be reacted with theprepolymer include polyol(s), amino-alcohol(s), a primary or secondarydiamine(s) or polyamine(s), hydrazine(s) or a substituted hydrazine(s).

Examples of such chain extenders useful herein include alkylene diaminessuch as ethylene diamine and cyclic amines such as isophorone diamine.Also materials such as hydrazine, azines such as acetone azine,substituted hydrazines such as, for example, dimethyl hydrazine,1,6-hexamethylene-bis-hydrazine, carbodihydrazine, hydrazides ofdicarboxylic acids and sulphonic acids such as adipic acid mono- ordihydrazide, oxalic acid dihydrazide, isophthalic acid dihydrazide,hydrazides made by reacting lactones with hydrazine such asgammahydroxylbutyric hydrazide, bis-semi-carbazide, and bis-hydrazidecarbonic esters of glycols may be useful. Water itself may be effectiveas an indirect chain extender.

Where the chain extender is other than water, for example a polyol,polyamine or hydrazine, it may be added to the aqueous dispersion ofprepolymer or, alternatively, it may already be present in the aqueousmedium when the prepolymer is dispersed therein. The prepolymer may alsobe chain extended to form the polyurethane polymer while dissolved inorganic solvent (usually acetone) followed by the addition of water tothe polymer solution until water becomes the continuous phase and thesubsequent removal of the solvent by distillation to form an aqueousdispersion.

The chain extension can be conducted at elevated, reduced or ambienttemperatures. Convenient temperatures are from about 5° C. to 95° C. or,more preferably, from about 10° C. to 60° C.

The total amount of chain extender materials employed (apart from water)should be such that the ratio of active hydrogens in the chainextender(s) to isocyanate groups in the prepolymer preferably being inthe range from 0.1:1 to 2.0:1 more preferably 0.80:1 to 1.7:1.

The not autoxidbisaly crosslinkable vinyl polymers bearing carbonylfunctional groups of component (ii) may be formed by he free-radicaladdition polymerisation of at least one carbonyl-containingmonoethylenically unsaturated monomer with at least one otherolefinically unsaturated monomer not providing carbonyl functionality.

Examples of unsaturated monomers which bear carbonyl functional groupsinclude acrolein, methacrolein, diacetone-acrylamide, crotonaldehyde,4-vinylbenzaldehyde, vinyl alkyl ketones of 4 to 7 carbon atoms such asvinyl methyl ketone, and acryloxy- and methacryloxy-alkyl propanols.Further examples include acrylamidopivalaldehyde,methacrylamidopivalaldehyde, 3-acrylamidomethylanisaldehyde, diacetoneacrylate, and diacetone methacrylate.

The proportion of carbonyl functional groups in the vinyl polymer ispreferably 3 to 200 milliequivalents per 100 g polymer, more preferably6 to 100 milliequievalents per 100 g polymer.

Examples of non-carbonyl-providing olefinically unsaturated monomersinclude 1,3-butadiene, isoprene, styrene, divinyl benzene,acrylonitrile, methacrylonitrile, vinyl halides (such as vinylchloride), vinyl esters (such as vinyl acetate, vinyl propionate andvinyl laurate), hetero cyclic vinyl compounds, alkyl esters ofmonolefinically unsaturated dicarboxylic acids (such as di-n-butylmaleate and di-n-butyl fumarate) and, in particular, esters, of acrylicacid and methacrylic acid, examples of which are methyl acrylate, methylmethacrylate, ethyl acrylate, ethyl methacrylate, n-butyl acrylate,n-butyl methacrylate, 2-ethylhexyl acrylate, 2-ethylhexyl methacrylate,isopropyl acrylate, hydroxyethyl methacrylate, hydroxypropylmethacrylate, isopropyl methacrylate, n-propyl acrylate and n-propylmethacrylate.

Olefinically unsaturated monomers bearing anionic water-dispersinggroups may also be used, examples of which include acrylic acid,methacrylic acid, itaconic acid and/or maleic acid.

Olefinically unsaturated monomers having non-ionic groups, such asalkoxy polyethylene glycol methacrylates, may also be used.

The not autoxidisably crosslinkable vinyl polymer may bear in additionto the carbonyl functional groups, amine and/or hydrazine functionalgroups as mentioned above (although this is not preferred). Hydrazinefunctional groups may preferably be introduced by polymerising into thevinyl polymer at least one olefinically unsaturated monomer with(chain-pendant) hydrazinolysable groups which are subsequently reactedwith a hydrazine yielding agent to convert at least a proportion of thehydrazinolysable groups into hydrazine functional groups.

Examples of monomers providing chain-pendant hydrazinolysable groupsinclude α-chloracrylic acid and especially acid chlorides or esters ofacryl acid, and also acid chlorides or esters of methacrylic acid.Preferred methacrylic acid esters are methyl, ethyl, propyl, isopropyl,n-butyl, tertiary or secondary butyl esters, most preferred are methyland ethyl esters.

The hydrazine content (if present) of the vinyl polymer is typically upto 300 milliequivalents per 100 g polymer, preferably 10 to 200milliequivalents per 100 g polymer.

Hydrazinolysis may be effected by dissolving or dispersing the vinylpolymer in a water-miscible alcohol or a water-alcohol mixture followedby the addition of hydrazine or hydrazine hydrate.

A vinyl polymer bearing carbonyl functionality may be prepared by anysuitable free-radical initiated polymerisation technique, a free-radicalinitiator and appropriate heating (e.g. 40° C. to 90° C.) beingemployed. The polymerisation is normally effected in an aqueous medium,and in particular aqueous emulsion polymerisation is used to prepare thepolymer with optionally conventional dispersants being used. Freeradical initiators include hydrogen peroxide, t-butylhydroperoxide,persulphates such as NH₄ persulphate K persulphate and Na persulphate ora redox system may be used.

Not autoxidisably crosslinkable vinyl polymers bearing carbonylfunctional groups for use in the invention preferably have a weightaverage molecular weight within the range 1000 to 5,000,000 (moreusually 2,000 to 1,000,000). The weight average molecular weight may bemeasured by gel permeation chromatography (gpc).

Preferably polyamines or polyhydrazines used to crosslink carbonylfunctional groups present in the composition are incorporated intocomponents (i) and/or (ii) before mixing the components, or after orduring the mixing of components (i) and (ii), as discrete entities.

Preferred polyamines include but are not limited to those with primaryand/or is secondary amino groups having from 2 to 10 such amino groupsper molecule. Especially preferred are primary amines. Suitable examplesinclude ethylenediamine, 4-amino-1,8-octanediamino propylenediamine,decamethylene diamine, 1,2-diaminocyclohexane, isophoronediamine, urea,N-(2-hydroxyethyl)ethylenediamine, tris(2-aminoethyl)amine, melamine,diethylenetriamine, dipropylenetriamine dibutylenetriamine, polyethyleneimines and Jeffamines (polyoxyethylene amines available from HuntsmanCorporation, Houston, Tx.).

Preferred polyhydrazines include but are not limited to dicarboxylicacid bis-hydrazides, bis-hydrazones, specific examples being oxalic aciddihydrazide, malonic acid dihydrazide, succinic acid dihydrazide, adipicacid dihydrazide, and sebacic acid dihydrazide, cyclohexane dicarboxylicacid bis-hydrazides, azelaic acid bis-hydrazides; also carbonic acidhydrazides, bis-semicarbazides, trihydrazides, dihydrazinoalkones anddihydrazines of aromatic hydrocarbons, for example1,4-dihydrazinobenzene and 2,3-dihydrazinonophthalene, dihydrazine andothers known in the art. Preferred examples include adipic aciddihydrazide and carbonic acid dihydrazides.

If discrete polyamines or polyhydrazines are added to the composition,the level is preferably that to provide a range of 0.02 to 1.6 molesmore preferably 0.05 to 0.9 moles of amine or hydrazine groups presentper mole of carbonyl functional groups present in the composition.

Component (ii), in addition to the at least one not autoxidisablycrosslinkable vinyl polymer bearing carbonyl functional groupsoptionally comprises a further not autoxidisably crosslinkable polymeror polymer moiety. Suitable not autoxidisably crosslinkable polymersinclude vinyl polymers not bearing carbonyl functional groups,polyurethane polymers not bearing carbonyl functional groups and/orpolyurethane polymers bearing carbonyl functional groups.

Preferably the additional not autoxidisably crosslinkable polymer is apolyurethane polymer or polyurethane polymer moiety. If a notautoxidisably crosslinkable polyurethane polymer is included in thecomposition as part of component (ii) (see later) it may be made in thesame manner as the autoxidisably crosslinkable polyurethane as describedabove but without the introduction of unsaturated fatty acid bearingcompounds.

The additional not autoxidisably crosslinkable polymer or polymer moietyis a) optionally a discrete polymer (i.e. not covalently bonded to thenot autoxidisably crosslinkable vinyl polymer bearing carbonylfunctional groups), b) formed by in-situ polymerisation in the presenceof the at least one not autoxidisably crosslinkable vinyl polymerbearing carbonyl functional groups. Alternatively the not autoxidisablycrosslinkable vinyl polymer bearing carbonyl functional groups is formedby in-situ polymerisation in the presence of the additional polymer.

Alternatively the additional polymer may be grafted to the notautoxidisably crosslinkable vinyl polymer bearing carbonyl functionalgroups or may comprise a copolymerised moiety of the not autoxidisablycrosslinkable vinyl polymer bearing carbonyl functional groups.

The autoxidisably crosslinkable polymer of component (i) and the notautoxidisably crosslinkable polymer(s) of component (ii) of thecomposition of the invention may be brought together by any suitabletechnique.

For example an aqueous dispersion of component (i) and an aqueousdispersion of component (ii) may be mixed together with agitation. Theaqueous solution may also contain water-miscible organic solvents.

Alternatively the not autoxidisably crosslinkable vinyl polymer may beprepared in the presence of the autoxidisably crosslinkable polymer(component (i)). For example free-radical initiators may be added to adispersed mixture of component (i) and vinyl monomer(s) or vice versaand polymerisation to the vinyl polymer effected. Optionally the notautoxidisably crosslinkable vinyl polymer may be grafted to theautoxidisably crosslinkable polymer.

The weight ratio of organic polymer(s) of component (i) to the notautoxidisably crosslinkable vinyl polymer(s) bearing carbonyl functionalgroups in the composition is suitably in the range from 90:10 to 10:90more preferably of from 70:30 to 30:70.

Preferred pH ranges are 4 to 11, more preferably 6.5 to 9.5 andespecially 7 to 8.5.

Neutralisation agents which may be applied include organic bases, forexample hydroxides of lithium, sodium or potassium, and organic basesfor example ammonia or tertiary amines for example dimethyl ethanolamine and triethylamine morpholine.

It is preferred to store the invention composition in a closedcontainer, where due to the low amount of oxygen no significantcrosslinking of the autoxidisable polymer has been found to occur untilafter application. However, this is by no means always necessary andindeed it is possible to use the invention composition soon after itsproduction. After coating the composition the water evaporates, oxygenin the atmosphere initiates autoxidation and a dual crosslinkingreaction takes place.

The aqueous composition of the invention may be advantageously employedas coating compositions, (e.g. protective or adhesive coatingcompositions) for which purpose they may be further diluted with waterand/or organic solvents, or they may be supplied in more concentratedform by evaporation of water and/or organic components of the liquidmedium. As coating compositions, they may be applied to any substrateincluding wood, metals, glass, cloth, leather, paper, plastics, foam andthe like, by any conventional method including brushing, dipping, flowcoating, spraying, and the like.

Drier salts preferably comprise part of the composition. Examplesinclude polyvalent salts containing cobalt, calcium, copper, zinc, iron,zirconium and manganese as the cation and halides, nitrates, sulphates,acetates, napthenates or acetoacetonates as the anion. The amount ofdrier used is in the range from 0 to 1% metal content by weight of thecomposition.

The compositions may contain other conventional ingredients includingorganic solvents, pigments, dyes, emulsifiers, surfactants, thickeners,heat stabilisers, levelling agents, anti-cratering agents, fillers,sedimentation inhibitors, UV absorbers, antioxidants, waxes and the likeintroduced at any stage of the production process or subsequently. It ispossible to include an amount of an antimony oxide in the dispersions toenhance the fire retardant properties. The dispersions may also be usedas adhesives for materials such as polypropylene, polyester,polyurethane, leather and the like or as binding agents for variousparticulate materials.

The dispersions suitably have a solids contents of from about 20 to 60%by weight, preferably from about 25 to 45% by weight.

If desired, the compositions of the present invention may include otherpolymer dispersions for example polyurethane, polyamide, polyepoxide,polyvinyl acetate, polyethylene, polystyrene, polybutadiene, polyvinylchloride, polyacrylate and other homopolymer and copolymer dispersions.These can sometimes be prepared in-situ (for example by polymerisationof the monomers in the presence of the polyurethane polymer orprepolymer).

The weight ratio of the organic polymer of component (i) and component(ii), the not autoxidisably crosslinkable vinyl polymer(s) bearingcarbonyl functional groups to other included polymers in the compositionis preferably from 100:0 to 40:60, more preferably 100:0 to 70:30, mostpreferably 100:0.

There is still further provided according to the invention a coatedsubstrate having a coating obtainable or derived from an aqueouscrosslinkable coating composition comprising a dispersion as definedabove, and the use of such a composition for coating a substrate.

The present invention is now illustrated by the following examples.Unless otherwise specified, all parts and percentages are on a weightbasis.

Preparation of Autoxidisably Crosslinkable Organic Polymers ContainingUnsaturated Fatty Acid Residues=FATTY ACIDS 1 to 5

FATTY ACID 1 An Unsaturated Fatty Acid Residue Containing UrethaneDispersion

Stage 1 - Synthesis of a fatty acid residue containing polyester polyolfor incorporation into a polyurethane Components Ingredients parts byweight 1 Adipic acid 535.9 2 Prifac 8960 (a polyunsaturated fatty acid916.0 from Unichema) 3 1,4-Cyclohexane dimethanol 250.5 4Trimethylolpropane 411.7 5 Fascat 2005 (SnCl₂) 0.1 6 Cardura E10(Neodecanoic acid glycidyl 97.7 ester) 7 N,N-dimethylbenzylamine 1.9

Components 1, 2, 3 and 4 were charged to a 2.5 liter flask fitted with astirrer, condenser, nitrogen inlet and thermocouple. The resultantmixture was gradually heated to the reaction temperature of 215° C.Water of distillation was collected. At this reaction temperaturecomponent 5 was added and the mixture was esterified until an acid valueof 10.4 mg KOH/g was obtained. Subsequently the temperature was reducedto 170° C. and components 6 and 7 were added and reacted until an acidvalue of 0.1 mg KOH/g was obtained. The total reaction time was 12hours. The hydroxyl value of the polyester polyol was 76.8 mg KOH/g.

Stage 2—Synthesis of a Fatty Acid Residue Containing PolyurethanePrepolymer

An isocyanate terminated urethane prepolymer containing the polyesterpolyol prepared in Stage 1 was prepared as described below:

269.6 g of Desmodur W (4,4′-disycohexylmethane diisocyanate), 34.0 g ofa difunctional isocyanate-reactive non-ionic component with a jointhydroxy number and acid number of 87 and a propylene oxide/ethyleneoxide (PO/EO) ratio of 9/1, 34.0 g dimethylol propanoic acid (DMPA),342.4 g of the polyester polyol from stage 1 and 120.0 g of N-methylpyrrolidone (NMP) were added to a 1 liter 3 necked round bottom flask.The mixture was stirred under nitrogen. The mixture was heated to 55° C.and 4 drops of Dabco T-9 (a tin octoate catalyst from Air Products) wereadded. The mixture was then heated to 95° C. and kept at thistemperature for 1 hour. 4 Drops of Dabco T-9 were added and the mixturewas kept at 95° C. for another hour. 8.7 g sample was taken forisocyanate (—NCO) determination. The residual NCO content was 5.05%. Thebatch was cooled down to 75°C.

25.6 g of triethylamine (TEA) and 10.2 g of Dapro 5005 (manganese driersalt mixture) were added to the prepolymer. The mixture was kept at thistemperature for 40 minutes.

Stage 3—Preparation of a Polyurethane Dispersion from the PolyurethanePrepolymer Prepared in Stage 2.

600.0 g of the prepolymer prepared in Stage 2 was added to a waterphaseconsisting of 820.7 g demineralised water and 19.6 g of Atlas G4809 anonionic alkoxylated alkylphenol surfactant (70%). The total additiontime was 65 minutes. The prepolymer was kept at 70-75° C. during theaddition to the waterphase, the temperature of the waterphase was 30-32°C.

When the addition was complete, a mixture of 15.6 g of hydrazine hydrate(63.7%) and 25 g of demineralised water was added to the dispersion. Thetemperature of the dispersion increased to 40° C. and was kept at thistemperature for 30 minutes. The batch was cooled to room temperature andsieved through a 200 mesh sieving cloth.

The dispersion had a solids content of 35%, pH of 8.1, viscosity of 210mPas at 25° C. and a sediment content of <0.05%.

FATTY ACID 2

A fatty Acid Residue Containing Low Molecular Weight (Non ChainExtended) Polyurethane

Stage 1—Preparation of Amide Ester Diol Products from Soybean Oil

A reactor was charged with 148.8 g diethanolamine and 1.2 g sodiummethoxide and the mixture was heated to 90-100° C. until all of thesodium methoxide had dissolved.

Subsequently, 750 g soyabean oil (available from Alnor Oil company) wasadded to the mixture followed by stirring and heating to 105-110° C. for4.5 hours.

Gel Permeation Chromatography (GPC) of the amide ester diol productshowed its composition to consist of 10.7% unreacted soyabean oil, 41.5%diglyceride mono-ol and 47.8% monoglyceride amide diol (ester amidepolyol). The theoretical hydroxy equivalent weight of the amide esterdiol product was 211 and corresponding OH number was 266 mg KOH/g.

Stage 2—Preparation of a Uralkyd Resin

116.3 g of the amide ester diol product from Stage 1 was mixed in areactor with 18 g 2,2-dimethylolpropionic acid, 12.8 gcyclohexanedimethanol, 20.3 g methoxypolyethyleneoxide glycol (MPEG750),134.2 g N-methylpyrrolidone, and 118.3 g toluene diisocyanate. Thetemperature was maintained at 50-60° C. for one hour. Then more amideester diol product (133.7 g) was added and the temperature increased to70-80 C. for two hours.

Stage 3—Preparation of an Aqueous Uralkyd Resin Dispersion

The product from Stage 2 was diluted with 76.7 g dipropylene glycolmonomethyl ether (acting as a cosolvent to reduce viscosity) and 9.55 gdimethylethanolamine dissolved in 187 g water (base for neutralisingcarboxyl groups). 5.6 g Drier salt (Dapro 5005, available from DanielsProducts) followed by 520 g water at 60° C. was added to the mixturewhile stirring.

The resulting dispersion had a clear, transparent yellow colour with aviscosity of 1640 mPa.s at 25° C., a pH of 7.1 and solids content of31%.

FATTY ACID 3 An Autoxidisably Crosslinkable Polyester ContainingUnsaturated Fatty Acid Residues

Worlésol 31A (available from Worlé-Chemie GmbH) is an anionicallystabilised polyester alkyd resin containing unsaturated fatty acidresidues, neutralised with ammonia and is supplied as a solution in awater/butylglycol mixture (80/20). The resin has a solid content of45.9%, a viscosity at 20° C. of 127 s (according to DIN 53211), the acidnumber on solids is 100.3 mg KOH/g and pH is 7.8. This solution was usedas supplied.

FATTY ACID 4 An Autoxidisably Crosslinkable Urethane DispersionContaining Unsaturated Fatty Acid Residues

NeoRez R2001 (available from NeoResins, Avecia BV) is a chain extendedurethane dispersion containing unsaturated fatty acid residues. (NeoRezand NeoResins are Trade Marks of Avecia BV). The fatty acid content isapproximately 35% on solids. The dispersion has a solids content of34.9%, pH was 7.8 and the viscosity was 220 mPa.s. This dispersion wasused as supplied.

FATTY ACID 5

An Autoxidisably Crosslinkable Urethane-acrylic Hybrid DispersionContaining Unsaturated Fatty Acid Residues

XR9405 (available from Avecia Inc) is a urethane-acrylic hybriddispersion containing unsaturated fatty acid residues. The fatty acidcontent is approximately 40% on solids. The dispersion has a solidscontent of 30%, pH was 7.6 and the viscosity was 212 mPa.s. Thisdispersion was used as supplied.

Synthesis of Not Autoxidisably Crosslinkable Vinyl Dispersions BearingCarbonyl Functional Groups=NAVP's 6 to 9 NAVP 6 A Not AutoxidisablyCrosslinkable Vinyl Dispersion Bearing Carbonyl Functional Groups

912 g of demineralised water and 1.82 g of sodium lauryl sulphate, (30w/w) were added to a three necked round bottom flask, equipped with athermometer, stirrer, cooler and a N₂ inlet. The mixture was heated to70° C. under N₂ atmosphere.

5% of a monomer mixture consisting of 188.2 g of demineralised water,5.45 g of sodium lauryl sulphate (30% w/w), 6.98 g of lauryl mercaptane,3.49 g of mercapto propionic acid, 43.61 g of methacrylic acid, 34.88 gof diacetone acrylamide and 357.56 g of methylmethacrylate was added tothe reactor. The reactor content was then heated to 80° C.

30% of a solution of ammonium persulphate (87.2 g, 1.5% w/w) in waterwas added to the reactor. The reactor content was heated to 85° C. andmixed at this temperature for 5 minutes.

The remainder of the monomer mixture was added to the reactor after 60minutes, and the remainder of the ammonium persulphate solution wasadded to the reactor after 70 minutes. The reactor content was kept at85° C. during this period. After the addition was complete, the reactorcontent was held at 85° C. for another 30 minutes.

A solution of 34.50 g of ammonia (25% w/w) and 124.4 g of demineralisedwater was added to the reactor. The reactor content was held at 85° C.for another 20 minutes. After this the batch was cooled down to roomtemperature and sieved through a 200 mesh sieve cloth. The pH was 7.8and the viscosity was 19 mPas at 25° C.

1034.5 g of this polymer dispersion was mixed with 195.38 g ofdemineralised water for 15 minutes at room temperature. 0.22 g ofdimethylethanol amine, 157.51 g of butylmethacrylate, and 48.58 g ofbutylacrylate and 6.38 g of diacetone acrylamide were added to thereactor, followed by 1.84 g of tert.-butylhydroperoxide (30% solution inwater w/w) and 2.80 g of a 1% (w/w) solution of ironethylenediaminetetraacetate (FeEDTA) in water. The reactor content washeated to 35° C. and mixed for 60 minutes.

2.69 g of a 3.96% (w/w) solution of i-ascorbic acid in water was addedand the reactor content was heated to 57° C. in 25 minutes. The batchwas held at this temperature for 15 minutes.

Then 36.98 g of a 1.21% (w/w) solution of i-ascorbic acid in water wasadded to the reactor in 30 minutes at 57° C. The batch was mixed for 15minutes and cooled down to 35° C.

A mixture of dimethyl ethanol amine (0.22 g), butyl methacrylate (157.5g) diacetone acrylamide (6.4 g) and butyl acrylate (48.6 g) was added tothe reactor. 1.84 g of tert.-butylhydroperoxide (30% solution in waterw/w), 2.80 g of a 1% (w/w) solution of FeEDTA in water and 230.95 g ofdemineralised water were added to the reactor and mixed for 60 minutesat 35° C. 2.69 g of a 3.96% (w/w) solution of i-ascorbic acid in waterwas added to the reactor content. The batch was heated to 42° C. andmixed at this temperature for 15 minutes.

Then 36.98 g of a 1.21% (w/w) solution of i-ascorbic acid in water wasadded to the reactor in 30 minutes at 42° C.

The batch was mixed for 30 minutes at 40° C. and a solution of 15.20 gof adipic dihydrazide and 14.13 g of demineralised water was addedbefore mixing for a further 30 minutes at 40° C., cooled down to roomtemperature and sieved through a 200 mesh sieve cloth.

The specifications of this batch were as follows: solids content 35%, pHof 7.8 and viscosity of 18 mPas at 25° C.

NAVP 7 A Not Autoxidisably Crosslinkable Acrylic Dispersion BearingCarbonyl Functional Groups

859.8 g of demineralised water, 14.0 g of sodium lauryl sulphate (30w/w), 1.69 g ammonium persulphate and 1.03 g of ammonium bicarbonate(25% w/w) were added to a three necked round bottom flask, equipped witha thermometer, stirrer, cooler and a N₂ inlet. 10% of a monomer mixtureconsisting of 242.0 g of demineralised water, 28.1 g of sodium laurylsulphate (30% w/w), 2.53 g ammonium persulphate, 2 g ammoniumbicarbonate (25% w/w), 50.5 g diacetone acrylamide, 33.7 g methacrylicacid, 421.2 g butylmethacrylate, 157.8 g butylacrylate and 179.1 gstyrene was added to the reactor. This mixture was heated to 80° C.under N₂ atmosphere and mixed at this temperature for 20 minutes. Theremainder of the monomer mixture was added to the reactor over a periodof 90 minutes. The reactor content was kept at 80° C. during thisperiod. After the addition was complete, the reactor content was held at80° C. for another 30 minutes. A solution of 3.08 g of ammonia (25% w/w)and 3.34 g of demineralised water was added to the reactor. The reactorcontent was held at 80° C. for another 30 minutes. After this the batchwas cooled down to room temperature and sieved through a 200 mesh sievecloth.

The pH was 6.7 and the viscosity was 400 mPa.s at 25° C. To 1000 g ofthis dispersion adipic acid dihydrazide (9.1 g) was added as acrosslinker.

NAVP 8 A Not Autoxidisably Crosslinkable Acrylic Dispersion BearingCarbonyl Functional Groups

859.8 g of demineralised water, 14.0 g of sodium lauryl sulphate(30w/w), 1.69 g ammonium persulphate and 1.03 g of ammonium bicarbonate(25% w/w) were added to a three necked round bottom flask, equipped witha thermometer, stirrer, cooler and a N₂ inlet. 10% of a monomer mixtureconsisting of 242.0 g of demineralised water, 28.1 g of sodium laurylsulphate (30% w/w), 2.53 g ammonium persulphate, 2 g ammoniumbicarbonate (25% w/w), 25.3 g diacetone acrylamide, 33.7 g methacrylicacid, 421.2 g butylmethacrylate, 162 g butylacrylate and 200.3 g styrenewas added to the reactor. This mixture was heated to 80° C. under N₂atmosphere and mixed at this temperature for 20 minutes. The remainderof the monomer mixture was added to the reactor over a period of 90minutes. The reactor content was kept at 80° C. during this period.After the addition was complete, the reactor content was held at 80° C.for another 30 minutes. A solution of 3.08 g of ammonia (25% w/w) and3.34 g of demineralised water was added to the reactor. The reactorcontent was held at 80° C. for another 30 minutes. After this the batchwas cooled down to room temperature and sieved through a 200 mesh sievecloth. The pH was 6.5 and the viscosity was 49 mPa.s at 25° C. To 1000 gof this dispersion 4.6 g of adipic acid dihydrazide was added as acrosslinker.

NAVP 9 A Not Autoxidisably Crosslinkable Urethane-acrylic Hybrid BearingCarbonyl Functional Groups in the Acrylic Polymer

Stage 1—Synthesis of a Polyurethane Prepolymer

An isocyanate terminated urethane prepolymer was prepared as describedbelow:

632 g IPDI (isophorone diisocyanate), 88 g dimethylol propanoic acid(DMPA), 880 g of a polypropylene glycol diol with an average molecularweight of 1600 g/mole (OH number=77.4 mg KOH/g) and 4 drops of Dabco T-9(a tinoctoate catalyst from Air Products) were added to a 2 liter 3necked round bottom flask. The mixture was stirred under nitrogen andheated to 95° C. and kept at this temperature until the practical NCOcontent reached 7.7% (g NCO/g prepolymer). The batch was cooled down to70° C. 54.8 g TEA was added to the prepolymer and the mixture was keptat this temperature for 1 hour.

Stage 2—Preparation of a Polyurethane Dispersion from the PolyurethanePrepolymer Prepared in Stage 1

650 g of prepolymer prepared in Stage 1 was added to a water phaseconsisting of 977.9 g demineralised water and 16.25 g of the surfactantSynperonic NP9 (available from ICI Surfactants). The total addition timewas 70 minutes. When the addition was complete, a mixture of 27.0 g ofhydrazine hydrate (63.5%) and 27 g water was added to the dispersion.The temperature of the dispersion increased to 41° C. and was kept atthis temperature for 30 minutes. The batch was cooled down to roomtemperature and sieved through a 200 mesh sieving cloth. The dispersionhad a solids content of 39%, pH was 7.4 and viscosity at 25° C. was 160mPa.s.

Stage 3—Synthesis of a Non-autoxidisably Crosslinkable Urethane-acrylicHybrid Bearing Carbonyl Functional Groups from the PolyurethaneDispersion of Stage 2

55.6 g butyl methacrylate, 12.2 g methyl methacrylate, 10.1 g diacetoneacrylamide and 130 g demineralised water were added to 400 g ofpolyurethane dispersion from stage 2 and slowly heated to 36° C. Then0.35 g of a Fe(II)EDTA solution (1% w/w in water), 5.1 g of a tertiarybutyl hydroperoxide solution (4.7% w/w in water) and 22.6 g iso-ascorbicacid solution (1% w/w in water) was added. The temperature was increasedto 48° C. and was kept on this temperature for 18 minutes and cooled toroom temperature. 55.6 g butyl methacrylate, 12.2 g methyl methacrylate,10.1 g diacetone acrylamide and 130 g demineralised water weresubsequently added and slowly heated to 31° C. and 22.6 g iso-ascorbicacid solution (1% w/w in water) was added. The temperature was increasedto 35° C. and 11.3 g iso-ascorbic acid solution (1% w/w in water) wasadded and kept on this temperature for 13 minutes and again 11.3 giso-ascorbic acid solution (1% w/w in water) was added and temperaturewas kept on 32° C. for 1 hour. The resulting urethane-acrylic hybriddispersion was cooled down to room temperature and sieved through a 200mesh sieving cloth. The dispersion had a solids content of 35.2%, pH was7.8 and viscosity at 25° C. was 40 mPa.s. To 400 g of this dispersion3.3 g of adipic acid dihydrazide was added as a crosslinker.

Comparative Vinyl-polymers

Preparation of Not Autoxidisably Crosslinkable Vinyl Polymers NotBearing Carbonyl Functional Groups=CVP's 10 to 12

CVP 10 A Not Autoxidisably Crosslinkable Acrylic Dispersion Not BearingCarbonyl Functional Groups

911.86 g of demineralised water and 1.82 g of sodium lauryl sulphate(30% w/w) were added to a three necked round bottom flask, equipped witha thermometer, stirrer, cooler and a N₂ inlet. The mixture was heated to70° C. under N₂ atmosphere.

5% of a monomer mixture consisting of 188.2 g of demineralised water,5.45 g of sodium lauryl sulphate 30% (w/w), 6.98 g of lauryl mercaptane,3.49 g of mercapto propionic acid, 43.61 g of methacrylic acid and392.44 g of methylmethacrylate was added to the reactor. The reactorcontent was then heated to 80° C.

30% of a solution of ammonium persulphate (87.2 g, 1.5% w/w) in waterwas added to the reactor. The reactor content was heated to 85° C. andmixed at this temperature for 5 minutes.

The remainder of the monomer mixture was added to the reactor after 60minutes, the remainder of the ammonium persulphate solution was added tothe reactor after 70 minutes. The reactor content was kept at 85° C.during this period. After the addition was complete, the reactor contentwas held at 85° C. for another 30 minutes.

A solution of 34.50 g of ammonia (25% w/w) and 124.4 g of demineralisedwater was added to the reactor. The reactor content was held at 85° C.for another 20 minutes. After this the batch was cooled down to roomtemperature and sieved through a 200 mesh sieve cloth. The pH was 8.3and the viscosity was 12 mPas at 25° C.

1055.60 g of this polymer dispersion was mixed with 184.15 g ofdemineralised water for 15 minutes at room temperature in the same typeof three necked round bottom flask. 0.22 g of dimethylethanol amine and170.34 g of butylmethacrylate and 46.55 g of butylacrylate were added tothe reactor, followed by 1.88 g of tert.-butylhydroperoxide (30%solution in water w/w) and 2.86 g of a 1% (w/w) solution of ironethylenediaminetetraacetate (FeEDTA) in water. The reactor content washeated to 35° C. and mixed for 60 minutes.

2.75 g of a 3.96% (w/w) solution of i-ascorbic acid in water was addedand the reactor content was heated to 57° C. in 25 minutes. The batchwas held at this temperature for 15 minutes.

Then 37.75 g of a 1.21% (w/w) solution of i-ascorbic acid in water wasadded to the reactor in 30 minutes at 57° C. The batch was mixed for 15minutes and cooled down to 35° C.

A mixture of dimethyl ethanol amine (0.22 g), butyl methacrylate (170.4g) and butyl acrylate (46.5 g) was added to the reactor. 1.88 g oftert.-butylhydroperoxide (30% solution in water w/w), 2.86 g of a 1%(w/w) solution of FeEDTA in water and 235.77 g of demineralised waterwere added to the reactor and mixed for 60 minutes at 35° C. 2.75 g Of a3.96% (w/w) solution of i-ascorbic acid in water was added to thereactor content. The batch was heated to 42° C. and mixed at thistemperature for 15 minutes.

Then 37.75 g of a 1.21% (w/w) solution of i-ascorbic acid in water wasadded to the reactor in 30 minutes at 42° C.

The batch was mixed for 30 minutes at 40° C., cooled down to roomtemperature and sieved through a 200 mesh sieve cloth.

The specifications of this batch were as follows: solids content 35%, pHof 7.9 and viscosity of 24 mPas at 25° C.

CVP 11 A Not Autoxidisably Crosslinkable Acrylic Dispersion Not BearingCarbonyl Functional Groups

859.8 g of demineralised water, 14.0 g of sodium lauryl sulphate(30w/w), 1.69 g ammonium persulphate and 1.03 g of ammonium bicarbonate(25% w/w) were added to a three necked round bottom flask, equipped witha thermometer, stirrer, cooler and a N₂ inlet. 10% of a monomer mixtureconsisting of 242.0 g of demineralised water, 28.1 g of sodium laurylsulphate (30% w/w), 2.53 g ammonium persulphate, 2 g ammoniumbicarbonate (25% w/w), 33.7 g methacrylic acid, 421.2 gbutylmethacrylate, 166.1 g butylacrylate and 221.4 g styrene was addedto the reactor. This mixture was heated to 80° C. under N₂ atmosphereand mixed at this temperature for 20 minutes. The remainder of themonomer mixture was added to the reactor during 90 minutes. The reactorcontent was kept at 80° C. during this period. After the addition wascomplete, the reactor content was held at 80° C. for another 30 minutes.A solution of 3.08 g of ammonia (25% w/w) and 3.34 g of demineralisedwater was added to the reactor. The reactor content was held at 80° C.for another 30 minutes. After this the batch was cooled down to roomtemperature and sieved through a 200 mesh sieve cloth. The pH was 6.5and the viscosity was 36 mPa.s

CVP 12 A Not Autoxidisably Crosslinkable Urethane-acrylic HybridDispersion Not Bearing Carbonyl Functional Groups

66.6 g butyl methacrylate, 11.5 g methyl methacrylate and 130 gdemineralised water were added to 400 g of polyurethane dispersion fromstage 2 from Example 10 and slowly heated to 35° C. Then 0.35 g of aFe(II)EDTA solution (1% w/w in water), 5.1 g of a tertiary butylhydroperoxide solution (4.7% w/w in water) and 22.6 g iso-ascorbic acidsolution (1% w/w in water) was added. The temperature was increased to44° C. and was kept on this temperature for 18 minutes and cooled toroom temperature. 66.6 g butyl methacrylate, 11.5 g methyl methacrylateand 130 g demineralised water were subsequently added and slowly heatedto 34° C. and 22.6 g iso-ascorbic acid solution (1% w/w in water) wasadded. 11.3 g iso-ascorbic acid solution (1% w/w in water) was added andkept on this temperature for 13 minutes and again 11.3 g iso-ascorbicacid solution (1% w/w in water) was added and temperature was kept on33° C. for 1 hour. The resulting urethane-acrylic hybrid dispersion wascooled down to room temperature and sieved through a 200 mesh sievingcloth. The dispersion had a solids content of 35%, pH was 8.2 and theviscosity at 25° C. was 50 mPa.s at 25° C.

Examples 1 to 30 and Comparative Examples C1 to C25

Preparation of compositions according to the invention were carried outby blending at room temperature the autoxidisably crosslinkable organicpolymers containing unsaturated fatty acid residues [FATTY ACIDS 1 to 5]with the not autoxidisably crosslinkable vinyl polymers bearing carbonylfunctional groups [NAVP's 6 to 9].

Comparative examples C1 to C25 were prepared by blending theautoxidisably crosslinkable organic polymers containing unsaturatedfatty acid residues [FATTY ACIDS 1 to 5] with not autoxidisablycrosslinkable vinyl polymers not bearing carbonyl functional groups[CVP's 10 to 12], at room temperature.

The composition and the properties of resultant coatings are shown belowin Tables 1 to 6.

i) Resistance The blends were cast down on Leneta test charts Form 2Cwith a film thickness of 100 μm. The films were dried at roomtemperature for 20 minutes and at 50° C. for 64 hours. After they werecooled down to room temperature the films were tested for “householdchemical resistance”.

a) Drops of the various testing liquids (water, ethanol, coffee and“Andy” a commonly used Dutch detergent) were placed on the films andcovered with a watch glass. The liquids were removed after 16 hours atroom temperature and the damage to the coating was assessed immediatelyand after four hours recovery. 0 means that the coating was dissolved, 5means that the coating was not affected at all.

For the hot pan test a drop of boiling water was placed on the film andcovered with a beaker containing boiling water for one hour beforeremoving the beaker and immediately assessing the film. 0 means that thecoating was dissolved, 5 means that the coating was not affected at all.

ii) BHMR=Black heel mark resistance: the coating is hit with a blackheel and the degree of damage to the coating was assessed the same asthe household chemical resistance is assessed.

iii) Yellowness (Yellow): 0 is very yellow, 5 is a colourless coating.

iv) Pencil hardness: was assessed according to ASTM D3363-92a. H numbersare hard and B numbers are soft on a scale from 8H to HB to B or less.

v) Hardness development: The Hardness was measured using a PendulumHardness Tester according to the König test method. The larger the valuethe harder the film was.

Examples 1 to 2 Blends of FATTY ACID 1 with NAVP 6 and ComparativeExamples C1 to C5: FATTY ACID 1, NAVP 6, CVP10 and Blends of FATTY ACID1 and CVP 10

TABLE 1 FATTY ACID 1/ Stain resistances vinyl vinyl polymer (assessmentafter 4 hrs) Example polymer ratio (w/w) BHMR Yellow Water EtOH CoffeeAndy C1 none 100/0  5 0 5* 5 5* 5 4 4 5* 5 C2 CVP 10  0/100 1 5 5* 5 2*2 4 4 1* 1 C3 NAVP 6  0/100 1 5 5* 5 4* 4 5 5 4* 4 C4 CVP 10 50/50 2 25* 5 1* 1 4 4 2* 3 1 NAVP 6 50/50 3 2 5* 5 2* 2 5 5 4* 5 C5 CVP 10 25/751 0 5* 5 1* 1 5 5 0* 0 2 NAVP 6 25/75 4 0 5* 5 2* 2 5 5 5  5 * =immediate assessment

TABLE 2 FATTY ACID 1/ Stain resistances Hardness Development vinyl vinylpolymer Pencil (assessment after 4 hrs) (room temperature) Examplepolymer ratio (w/w) BHMR Yellow Hardness Water EtOH Coffee Andy 3 hrs 6hrs 1 day 4 days 3 NAVP 7 25/75 3-4 — 5 H 5 5 4 4-5 27 45 87 99 4 NAVP 750/50 1 — 7 H 5 4 3-4 5 30 41 67 86 5 NAVP 8 25/75 2 — 5 H 5 4-5 4 5 3030 83 89 6 NAVP 8 50/50 0 — 6 H 5 4 3 5 27 39 71 73 C6 CVP 11 25/75 0 —5 H 4-5 0 4 3-4 24 37 64 74 C7 CVP 11 50/50 0 — 5 H 5 2 3-4 2-3 26 39 6779 7 NAVP 9 50/50 3-4 4-5 7 H 5 4 1 5 50 61 80 81 8 NAVP 9 25/75 2 5 8 H5 3 1 5 76 84 97 91 C8 CVP 12 50/50 1 2-3 5 H 5 4 1 1 53 70 80 84 C9 CVP12 25/75 0 2-3 7 H 4-5 4 2 1 61 73 77 80 — = not measured

TABLE 3 FATTY ACID 2/ Stain resistances Hardness Development vinyl vinylpolymer Pencil (assessment after 4 hrs) (room temperature) Examplepolymer ratio (w/w) BHMR Hardness Water EtOH Coffee Andy 3 hrs 6 hrs 1day 4 days  9 NAVP 7 50/50 3 6 H 4 3-4 2-3 4 11 11 37 — 10 NAVP 7 25/750-1 5 H 3-4 3 3 4-5 14 14 61 — 11 NAVP 8 50/50 2 7 H 3-4 1 2-3 4 11 1444 — 12 NAVP 8 25/75 0 7 H 3-4 3 3 4-5 10 17 54 — C10 CVP 11 50/50 0 5 H1-2 1 2-3 3 tacky 13 37 — C11 CVP 11 25/75 0 5 H 1-2 1 3-4 3-4 tacky 1757 — 13 NAVP 9 50/50 0 5 H 4 4 1 4-5 27 31 46 53 14 NAVP 9 25/75 1 8 H 54 1 5 43 50 59 64 C12 CVP 12 50/50 0 B 2 5 1 4 11 33 40 40 C13 CVP 1225/75 0 6 H 5 3 1 3 31 43 50 51 —= not measured

TABLE 4 FATTY ACID 3/ Stain resistances Hardness Development vinyl vinylpolymer Pencil (assessment after 4 hrs) (room temperature) Examplepolymer ratio (w/w) BHMR Yellow Hardness Water EtOH Coffee Andy 3 hrs 6hrs 1 day 4 days 15 NAVP 7 25/75 2 — <B 5 1 3 3  7  8 17 17 16 NAVP 750/50 0 — <B 2 1 1 1 tacky tacky tacky  9 C14 CVP 11 25/75 0 — <B 3 1 33  6  6  6 13 C15 CVP 11 50/50 0 — <B 1 1 1 1 tacky tacky tacky  6 17NAVP 9 50/50 0 1-2 <B 3 3 0-1 0 11 11 11 11 18 NAVP 9 25/75 1-2 2-3 <B4-5 4 1 4 16 17 17 17 C16 CVP 12 50/50 0 1-2 <B 2 3 1 0 11 11 11 11 C17CVP 12 25/75 0 1-2 <B 2 4 1 2 21 20 20 20 — = not measured

TABLE 5 FATTY Stain resistances ACID 4/ Pencil (assessment after 4 hrs)Hardness Development Exam- vinyl vinyl polymer Yel- Hard- hot Cof- (roomtemperature) ple polymer ratio (w/w) BHMR low ness pan Water EtOH feeAndy 3 hrs 4 hrs 6 hrs 1 day 2 days 4 days 19 NAVP 7 50/50 4 — — 4 4-54-5 4-5 19 54 63 — 20 NAVP 7 25/75 3 — — 2 4-5 4 4-5 17 50 63 — 21 NAVP8 50/50 3 — — 2 4-5 4-5 4-5 20 47 59 — 22 NAVP 8 25/75 0 — — 4 4 4 4-511 24 39 — C18 CVP 11 50/50 0 — — 4 2 2 2 13 43 47 — C19 CVP 11 25/75 0— — 3-4 3 3 2 13 39 41 — 23 NAVP 9 50/50 3-4 2-3 7 H 5 4 1 4-5 49 59 8190 24 NAVP 9 25/75 3-4 4-5 7 H 5 4 1 5 87 94 104 110 C20 CVP 12 50/50 01-2 7 H 5 4-5 2 3-4 41 63 70 79 C21 CVP 12 25/75 0 2-3 6 H 5 4-5 1 3 6973 74 80 — = not measured

TABLE 6 FATTY ACID 5/ Stain resistances Hardness Development vinyl vinylpolymer Pencil (assessment after 4 hrs) (room temperature) Examplepolymer ratio (w/w) BHMR Hardness Water EtOH Coffee Andy 3 hrs 6 hrs 1day 4 days 25 NAVP 7 50/50 0 6 H — 4 3-4 2 23 — 80 91 26 NAVP 7 25/75 06 H — 3 4-5 3 19 — 63 86 27 NAVP 8 50/50 0 6 H — 3 3-4 3 17 — 64 80 28NAVP 8 25/75 0 5 H — 3-4 4-5 3 19 — 66 91 C22 CVP 11 50/50 0 4 H — 2 42-3 19 — 64 73 C23 CVP 11 25/15 0 5 H — 1 4 2 14 — 67 89 29 NAVP 9 50/502 8 H 5 4 1 4 64 77 91 90 31 NAVP 9 25/75 2 8 H 5 4-5 1 4-5 83 91 103 103  C24 CVP 12 50/50 0 7 H 5 4 1 2 40 56 66 67 C25 CVP 12 25/74 0 7 H 54 1 1 64 74 79 77 — = not measured

What is claimed is:
 1. An aqueous crosslinkable coating compositioncomprising as aqueous dispersed components: (i) at least oneautoxidisably crosslinkable organic polymer containing unsaturated fattyacid residues, and (ii) at least one vinyl polymer which is notautoxidisably crosslinkable and bears carbonyl functional groups, andwherein said composition has present therein carbonyl reactive amineand/or hydrazine functional groups which impart crosslinkability tocomponent (ii).
 2. A composition according to claim 1 wherein component(i) is a polyurethane polymer.
 3. A composition according to claim 2wherein the polyurethane polymer has been formed by the chain extensionof an isocyanate-terminated polyurethane prepolymer with an activehydrogen chain extending compound.
 4. A composition according to any oneof claim 1, 2 or 3 wherein the functional amine or hydrazine groups areprovided by polyamines or polyhydrazines which are not part of theautoxidisably crosslinkable organic polymer or of the vinyl polymer. 5.A composition according to any one of claim 1, 2 or 3 wherein thehydrazine functional groups are provided by compounds selected fromdicarboxylic acid bis-hydrazides and hydrazones derived therefrom,carbonic acid hydrazides and bis-semicarbazides.
 6. A compositionaccording to any one of claim 1, 2 or 3 wherein the autoxidisablycrosslinkable organic polymer containing unsaturated fatty acid residuesalso bears chain-pendant carbonyl functional groups.
 7. A compositionaccording to any one of claim 1, 2 or 3 wherein the autoxidisablycrosslinkable polymer containing unsaturated fatty acid residues alsobears chain-pendant amine or hydrazine derivative functional groups. 8.A composition according to any one of claim 1, 2 or 3 wherein the vinylpolymer also bears chain pendant amine or hydrazine derivativefunctional groups.
 9. A composition according to any one of claim 1, 2or 3 wherein the ratio of amine or hydrazine derivative groups tocarbonyl functional groups is 0.02 to 1.6 moles of amine or hydrazinederivative groups per mole of carbonyl functional groups.
 10. Acomposition according to any one of claim 1, 2 or 3 wherein the ratio ofcomponent i) to component ii) is from 90:10 to 10:90.
 11. A coatedsubstrate having a coating obtainable from an aqueous crosslinkablecoating composition as claimed in any one of claim 1, 2 or
 3. 12. Themethod which comprises coating a substrate with an aqueous crosslinkablecoating composition as claimed in any one of claim 1, 2 or 3.